Moderator material for neutrons and use of said material

• US 5,703,918 A
• Filed: 06/10/1996
• Issued: 12/30/1997
• Est. Priority Date: 06/14/1993
• Status: Expired due to Term

• Current Assignee: Valtion Teknillinen Tutkimuskeskus
• Original Assignee: Radtek Oy
• Inventors: Auterinen, Iiro, Hiismaki, Pekka
• Primary Examiner(s): Wasil, Daniel D.
• Application Number:
  US08/571,892
• Time in Patent Office: 568 Days
• Field of Search: 376/458, 376/287, 376/288, 376/906, 376/340, 376/346, 250/515.1, 250/518.1, 252/478, 428/650, 428/654, 420/528, 423/489
• US Class Current: 376/458
• CPC Class Codes: A61N 2005/109 Neutrons
• CPC Class Codes: A61N 2005/1094 Shielding, protecting against radiation
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: G21C 5/12 characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator purification of fluid moderators during the operation of the reactor G21C19/30
• CPC Class Codes: G21K 5/04 with beam-forming means
• CPC Class Codes: H05H 3/06 Generating neutron beams targets for producing nuclear reactions H05H6/00; neutron sources G21G4/02
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors
• CPC Class Codes: Y10S 376/906 Metal
• CPC Class Codes: Y10T 428/12736 Al-base component

Abstract

The invention concerns a moderator material used for moderation of high-velocity neutrons, in particular of fission neutrons, to epithermal neutrons. The principal components of the moderator material are aluminum fluoride and aluminum metal, which have been formed into a dense composite substantially free of pores, wherein the material contains 20 to 50%-vol. of aluminum metal and 80 to 50%-vol. of aluminum fluoride. Further, the use of the moderator material in accordance with the invention in neutron capture therapy of cancer tumours is described, such as in boron neutron capture therapy (BNCT).

Claims

1. Moderator material used for moderation of high-velocity neutrons to epithermal neutrons, said moderator material comprising aluminum fluoride and aluminum metal, as a composite substantially free of pores.

2. Moderator material as claimed in claim 1, wherein said material contains from about 20 to 50% by volume of aluminum metal and from about 80 to 50% by volume of aluminum fluoride.

3. Moderator material as claimed in claim 2, said moderator material further comprising a continuous three-dimensional, network-formed matrix of aluminum metal wherein the remaining spaces of said network are substantially filled by aluminum fluoride.

4. Moderator material as claimed in claim 1, further comprising a substance that absorbs thermal neutrons and that does not produce high energy gamma rays.

5. Moderator material as claimed in claim 1 wherein said high velocity neutrons comprising fission neutrons.

6. Moderator material as claimed in claim 4, said substance comprising lithium fluoride.

7. Moderator material as claimed in claim 6, said lithium fluoride added to the moderator material in the amount of about 1% by volume.

8. Moderator material as claimed in claim 1, wherein said atomic ratio of aluminum to fluorine is greater than 1 to 3.

9. Moderator material as claimed in claim 1, said material formed by a method of hot isostatic pressing.

10. A method of neutron capture therapy of cancer tumors comprising the steps of:

providing a neutron source having a moderator material as claimed in claim 1 around said source; and

passing neutrons from the source through the moderator material into the body part of a patient to be treated, wherein said neutrons are not thermalized until in the interior of the body of the patient.

11. The method of claim 10 wherein said neutron capture therapy is boron neutron capture therapy.

12. The method of claim 10, wherein the neutron source is a research reactor which produces high-velocity fission neutrons, which are moderated under control to neutrons having an energy range of 1 eV to 10 keV.